Looking at the tutorial on VAEs (http://pyro.ai/examples/vae.html) it appears to me strange why the data is not binarized, even though the calculation of the likelihood of the image is supposed to be with respect to generation by a bernoulli distribution.

You could take a look at #529 for some context on this. It works out because of the way Bernoulli.log_prob is implemented which computes binary_cross_entropy, and hence can be passed a continuous value. A more elegant approach would be to use a distribution valued observation as discussed in #988.